Removing vowels from word in python

Question

My codes seems to work (I tested it in workspace) but I get the error message that the tester got back unexpected letters. Did I not understand the instructions correctly or what's wrong with my code?

BR, Kimmo

disemvowel.py

def disemvowel(word):
    List = list(word)
    Vowels = ["a", "e", "i", "o", "u"]
    for letter in List:
        if letter.lower() in Vowels:
            List.remove(letter)
    word = ''.join(List)
    return word

Answer 1 · 2017-08-14T14:51:29Z

August 14, 2017 2:51pm

Hi there! The reason the code in the original answer posted here worked and your code doesn't is that your code doesn't take into account what happens when you remove an item. Let's say that you are at index 2 and you remove that item. The item in index 3 moves down to the 2 place, and the 4 moves down to the 3 place. But your next iteration, you'll be looking at what's in place 3. So essentially, you are skipping a check on a letter.

I encourage you to run your script in workspaces and include this line

print(disemvowel("treehouse"))

What will be returned is "trhuse". Essentially, using the remove function messes up where the function is currently looking as far as index.

Hope this helps!

edited to remove a reference to an answer that no longer exists in this thread

Answer 2 · 2017-08-14T16:32:29Z

August 14, 2017 4:32pm

Repeat this mantra: "Never modify the iterable of a for loop"

As Jennifer Nordell mentioned it messes up the indexing and causes skipped iterable elements.

Workaround: iterate over a copy instead

# use built-in copy method
for letter in List.copy():
# or sliced copy – you learn about these next
for letter in List[:]:

A note about coding style:

variable names should be all lowercased names. Capitalization is used for class names.
a list is a built-in type and shouldn't be used for a variable name. Better to use a description of what the list contains, such as, "letters". This leads to the more readable:
```
for letter in letters:
```

Answer 3 · 2018-02-20T18:29:42Z

February 20, 2018 6:29pm

Lol, ah yes, it does! The solution doesn't use a list as you say. Mine felt awkwardly complex compared to this:

def disemvowel(word):
    vowels = "aeiouAEIOU";

   for char in vowels:
        word = word.replace(char, "")

    return word

Answer 4 · 2017-08-15T07:20:43Z

August 15, 2017 7:20am

Thanks Jennifer and Chris! I have a little of a hard time understanding why the script works if there are two vowels in a row and they're the same vowel, but not if there are different vowels in a row. I will, however, keep in mind not to mess with the iterable of a for loop :-).

Answer 5 · 2018-02-20T17:12:48Z

February 20, 2018 5:12pm

I don't know if anyone will see this, but I'm struggling hard to understand this. I followed a thread to this solution, so that is why I'm posting here.

def disemvowel(word):
    vowelList = ['a', 'e', 'i', 'o', 'u']
    wordList = list(word)
    for letter in wordList:
        if letter.lower() in vowelList:
            wordList.remove(letter)

    word = ''.join(wordList)
    return word

print(disemvowel('cAeUcdkpZs'))

My problem is, if I feed the function with the "Treehouse is awesome" string as suggested, this works. But if I use a string like this, which the task gives, it doesn't work. So I see its mentioned using a copy of the list. But I don't understand how that changes anything, cause will I not just have a copy of the list with the same problem of removing one character changes the "numbering" of the next? Bad wording, but if I remove vowels from 'RyOrE', the first one is O then the "indexing" of each one is changed? I guess indexing is the right thing to call it, since its a list?

I'm struggling, there is something I'm just not understanding. Very happy if anyone can elaborate. I don't know whats missing from my understanding.

Answer 6 · 2018-02-21T14:35:33Z

February 21, 2018 2:35pm

Big thanks Chris!

Answer 7 · 2019-01-03T15:30:19Z

January 3, 2019 3:30pm

Hi All,

I tried this solution with a try except block, can you suggest any better way of doing this.

def disemvowel(word):
    myList = list(word)
    vowels = ['a','e','i','o','u','A', 'E', 'I', 'O','U']

    for x in vowels:
        exitLoop = False
        while not exitLoop:
            try:
                myList.remove(x)
            except ValueError:
                exitLoop = True

    word = "".join(myList)
    return word

We could also modify it if we could use list.count() api.

Answer 8 · 2018-02-20T18:23:18Z

February 20, 2018 6:23pm

Huge thanks Jennifer. I did find a much more elegant solution which used a for loop instead. It seemed elegant in that it was less complex anyways. Thank you for taking the time of explaining this in such detail. The gotcha for me in your explanation was "iterate over one and change the other". Often it feels like its two steps ahead and one back hehe.

Edit: Yes, after looking at your code I finally understand it!

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Kimmo Ojala

Kimmo Ojala

Removing vowels from word in python

8 Answers

Jennifer Nordell

Jennifer Nordell

Ben Jakuben

Ben Jakuben

Jennifer Nordell

Jennifer Nordell

Chris Freeman

Chris Freeman

Thomas Bråten

Thomas Bråten

Chris Freeman

Chris Freeman

Kimmo Ojala

Kimmo Ojala

Jennifer Nordell

Jennifer Nordell

Chris Freeman

Chris Freeman

Thomas Bråten

Thomas Bråten

Jennifer Nordell

Jennifer Nordell

Thomas Bråten

Thomas Bråten

Animesh Bhadra

Animesh Bhadra

Thomas Bråten

Thomas Bråten

Jennifer Nordell

Jennifer Nordell